1. Field of the Invention
The present invention relates to carbon nanomaterials, and in particular, to a method of preparing carbon nanocages.
2. Description of the Related Art
Since fullerenes were discovered by Harold Kroto et al. in 1985 and the carbon nanotube was discovered by Sumio Iijima in 1991, carbon nanostructures have attracted significant interest.
Carbon nanocages are polyhedral carbon clusters that are comprised of several graphite layers. The carbon nanocages have a specific fullerene ball-within-a ball structure and optoelectronic properties. These properties make carbon nanocages appropriate for use as a medicinal grade active carbon, a light and heat absorbent material, an electromagnetic shielding material, an organic luminous material, a solar energy absorbent material, a catalyst, a sensor, a carbon electrode of lithium battery, a nanoscale composite material having superior heat conductivity and specific electrical properties, and a nanoscale carbon powder for printing, for example.
However, a method of mass-producing high purity carbon nanocages has not yet been developed. Although carbon nanocages can be prepared using conventional techniques such as carbon-arcing, ultrasonic treatment, high-energy irradiation, thermal treatment of fullerene black and plasma torch process, the yield of nanocage products is low and while the yield of various byproducts such as carbon nanotubes, carbon fibers and amorphous carbon is too high.
Catalytic chemical vapor deposition (CVD) is considered to be the most effective method for mass-producing carbon nanomaterials at a low cost. This method has superior controllability when compared to other methods.
A method of preparing carbon nanomaterials using an inexpensive, nontoxic, low energy carbon source is a goal that synthetic chemists have long pursued.
U.S. Pat. No. 6,063,243 discloses an arc discharge process that can produce carbon nanotubes along with nanoparticles as a byproduct. DE Patent No. 19740389 uses a catalytic deposition process with a laser beam to prepare carbon nanofibers, carbon nanoparticles and fullerenes. However, this method is costly and the yield of products is low. In addition, it is difficult to purify the products that are prepared by this method.